510 



ultra sonics, 134 



violet, 51, 65, 125, 140, 213, 382 

 umbilical cord, 262 

 union of nuclei, 50 

 Urechis, 45, 53, 68 



vertebrae, 262 



virus, 372, 375, 388, 389s, 399 



vital staining, 93, loi, 158s, 224, 226s 



vitelline membrance, 38, 42, 146 



SUBJECT INDEX 

 vrool, 259 



x-rays, 51, 141, 305, 306, 307, 333, 372, 373 



Y chromosomes, 36 



yeast, 401 



yolk, 5, 36, 58, 201 



gel membrane, 226, 229 



nucleus, 34, 36 



plug, 162 



Wolffian duct, 266, 268 



zip fastener, 446, 449 



